Conventionally, as a substrate detachment detection device used in a substrate processing apparatus in which substrate processing is performed by continuously rotating a rotary table in a state in which a substrate is loaded on a substrate mounting recess formed on the surface of the rotary table substantially horizontally installed in a chamber, a substrate detachment detection device having a substrate detachment determination means which determines whether the substrate has detached from the recess by determining the presence or absence of the substrate on the recess during the rotation of the rotary table is known.
In this substrate detachment detection device, a radiation thermometer for detecting the temperature of through holes for elevating pins installed in the recess for loading the substrate on the rotary table is installed to detect detachment of the substrate based on a temperature difference, or an imaging means for picking up an image of the recess is installed to detect detachment of the substrate. When the substrate is detached, the rotation of the rotary table is stopped.
However, in the related art, it is possible to detect that the substrate is detached but it is not possible to detect a state of the substrate which has a possibility to be detached but has not yet detached. Accordingly, in the related art, even though it may be possible to reduce damages in the chamber, such as reducing generation of defective wafers or the like by taking measures, it is impossible to completely prevent damages.